In the blustery days of late fall, the traveler still can find the sparseness and solitude that so greatly pleased the Concord naturalist in 1849

Anything built on top of the cliff is doomed. When Thoreau was there, three small brick lighthouses stood in a row above Nauset Beach, well back from the edge of the cliff. In 1892 they fell off the edge, to be replaced by three more and then, in 1923, by a single, taller lighthouse. The only reason that not many houses have fallen from the cliff is that early settlers did not build near the ocean. They built in the hollows, where they were sheltered from the wind, or along the bay side, where the water is calmer and the land lower. The men who lived in those houses were seamen, and they saw enough of the wild ocean from their ships without having to look at it from the land. The ocean side of the Cape was to them the back side.

On some stretches of the Cape, in recent times, vacation houses have been built close to the shore, and some of them are in trouble. As the beach in front of them washes away and the tide comes closer, the owners try different ways to do what King Canute could not do. They build seawalls, which may last for decades but not forever. They put in jetties or rocks or pilings, which may trap some sand for a while, but often at the expense of the neighbor’s beach. They may try sandbags or fences or nettings of wood or metal. At last, despairing, they may pick up their cottages and move them back from the shore. Sooner or later the ocean has its way.

Why, then, do people keep on building at the very edge of the sea, not only on Cape Cod but all along the coast? One might as well ask why the farmers on the slopes of Mount Vesuvius, after an eruption that has buried their land beneath volcanic ash, go right back and plant their fields. In the case of the farmers, the mountain slope is their home, and besides, the ash eventually enriches the land. The beach dwellers likewise are willing to take some risks for the joy of summers at the water’s edge. And they, too, have been enriched just by staying there. Today the extra value of a hundred front feet on the shore of Cape Cod is something like two hundred thousand dollars—that is, two hundred thousand dollars added to the price that the property would bring if it were not on the shore. There is hardly a shorefront lot outside the National Seashore and other reservations that has not been built upon.

The Park Service, which runs the National Seashore, has learned some deference to the forces of nature. Until 1978 visitors to Coast Guard Beach in Eastham parked on a low-lying stretch of beachfront, not far from the spit of land where Henry Beston wrote his Cape Cod classic, The Outermost House . The parking lot was torn to pieces by a great winter storm, which also carried away the Outermost House. It has not been rebuilt.

As they progressed along the Cape, Thoreau and Channing would walk for a stretch on the sand and then climb the cliff to walk on the plateau above. Here the law-abiding modern hiker often cannot follow them. In order to control erosion, the National Seashore Administration has put many sections of the land behind the dunes, as well as the cliff walls themselves, off limits. The dunes are held in place by the long, twisting roots of the beach grass; if the grass is trampled, it dies and the dunes become a moving desert.

Thoreau, who hated all restrictions, would not have liked being told where he could or could not walk. But if he were around today, he probably would admit that the National Seashore has saved Cape Cod. The park was established in 1961, in the nick of time, largely through the influence of President Kennedy.

The Seashore is unique among national parks in that it was superimposed on established towns that had been there since the time of the Pilgrims. About 60 percent of Wellfleet is in the park, and approximately 70 percent of Truro. The takeover of so much settled territory by the federal government was not accomplished without concessions to the towns and their residents. The towns retained control of their established beaches, which some of them close to outsiders. Owners of houses within the park may keep them or sell them freely, although they are discouraged from making any large additions. The Seashore Administration has been diligent about protecting the captive property owners from trespassers, but at the same time it brooks no violation of its rules. Four years ago the owner of one beach cottage, which was being threatened by the sea, moved it to higher ground without permission. While he was absent, a park crew demolished it.